Conventional selector assemblies used in avionic multifunctional displays generally include a user interface or knob and an encoder mechanism for sensing the pushing or turning of the knob. The knob and encoder mechanism are attached to a housing which can be employed partially above and below a Liquid Crystal Display (LCD).
Encoder mechanisms typically employ three sensors and two separate disk mechanisms to perform quadrature and push button functions. For example, selector assemblies can utilize three Hall-effect sensors or three optical emitter/detector pairs to detect manipulation of the knob. In a particular type of optically-based encoder mechanism, two emitter/detector pairs are positioned with respect to two rotating pattern disks fixed to the knob to sense the direction of rotation (i.e., quadrature, either clockwise or counterclockwise). A third emitter/detector pair, with its own separate physical mechanism, detects a push motion of the knob. The three sensors, each with separate mechanical mechanisms, generally require a high parts count, more complicated wiring, and increased manufacturing costs.
The separate disks used in current encoder mechanisms are configured to slide past each other. Since these disks have to be engaged and driven with a fair degree of accuracy, the parts also have to be relatively precisioned with close mechanical tolerances. Thus, the components in conventional encoder mechanisms are not only expensive but are also subject to wear. Moreover, there is also the potential for the shedding of materials and the clogging of apertures within the encoder mechanism. A further expense is then incurred in the maintenance of these component parts.
Conventional encoder mechanisms are typically designed to be placed inside the housing of the selector assembly. As a result, the encoder mechanism, with at least three sensors and separate physical mechanisms, increases the space required by the housing of the selector assembly. The large selector housing can interfere with space that would otherwise be available for display component parts, such as, the LCD glass.
Thus, there is a need for a selector assembly that does not use separate disk mechanisms for encoding a motion. Further, there is a need for a selector assembly that utilizes only two sensors to perform both quadrature and push button functions. Further still, there is a need for a selector assembly that places the physical components and the sensors of the encoder mechanism in the knob, thereby optimizing the usable glass surface area for avionic displays. Even further still, there is a need for placing the encoder pattern and the sensing mechanism within the knob of the selector assembly, whereby both the number of component parts and the associated production costs are minimized.